The present invention relates generally to a microscope stage capable of heating an entire culture vessel containing specimen such as cells or microorganism to be observed, and a microscope observing unit including the microscope stage and a culture device to be disposed on the stage.
It has been well known in the art to use shallow cylindrical dishes of a diameter of 35 mm as culture vessels for cells or microorganisms. Recently, there have been used culture vessels so called well plates having a number of cells or compartment, each well cells Accommodating a culture solution and cells or microorganisms. The typical dimension of the well plates is of a width of 85 mm and a length of 115 mm. Namely, the well plates are substantially larger than the dishes. The well plates have a variety of depths. As can be seen from above, there has been used culture vessels of various sizes in dependence upon their applications.
When it is intended to culture cells or microorganisms, it is required to keep a given temperature within the dishes or well plates, for example, at 37° C. It is further required to control atmosphere within the dishes or well plates in terms of CO2 concentration, the humidity and the like.
Generally, light microscopes are used for observation of cells and the like. When observing growing cells or microorganisms, it is required to heat a culture vessel accommodating the cells therein disposed on the microscope stage. In order to accomplish the heating of the vessel, commercially available is stage heaters adapted to be fit into the opening formed in the central portion of the microscope stage. Each stage heater includes a glass plate on which an electrically conductive transparent film applied. Upon energized, the film generates heat energy to heat the culture vessel disposed thereon.
However, especially for a well plate of larger size, the entire well plate is not heated by the commercial stage heaters, i.e. at least a portion of the well plate is not heated. This is because the stage heater as mentioned above is positioned only on the central portion of the microscope stage. Thus, a portion of the cells or microorganisms can not be disposed oppositely with the stage heater.
Further, for well plates, observation is done for each well cells Accommodating cell or microorganisms and culture solution. In this connection, it is required to displace the well plate repeatedly in order to align one well cell to be observed with the optical axis of the microscope objective lens by the cell number. It is cumbersome to displace the well plate manually. Further, it is difficult to displace the well plate precisely by hands. In this connection, it is requested to use a microscope stage of such a type that the base member, on which a culture vessel is disposed, can be shifted in two dimensional directions.
However, the two dimensionally movable microscope stage of this kind is relatively thick, since it is of a three-stage structure including a fixed base to be secured on the microscope, a lower base adapted to be movable in side to side direction (referred hereinafter to as x-direction), and an upper base adapted to be movable in back and force direction (referred hereinafter to as y-direction). If the stage heater of the type above mentioned is simply incorporated into the movable type microscope stage, the overall thickness of the microscope stage will further thicken. Thus, the distance between specimen in each well cell of a well plate disposed on the microscope stage and the objective lens is further increased in addition of the thickness of the stage heater. In this connection, it will be difficult or impossible to focus the objective lens on the specimen in each well cell, if as the microscope is a high-powered one. In other words, it will be difficult or impossible to focus the objective lens on specimen such as cells or microorganisms to be observed even if the objective lens is approached to its closet limit of the up-down or vertical direction (referred hereinafter to as z-direction). This is because the displace-able range of the objective lens in vertical direction is already be determined and limited on the basis of the microscope stage of a simple one-stage structure. Therefore, if the stage heater of the type above mentioned is simply incorporated into the movable type microscope stage, the objective lens can not be focused on specimen even under the approach-able limit.
Further, the condenser is also displaced relatively away from specimen to be observed because of the thickness of the movable type, three-stage microscope stage. In this connection, it will be difficult or impossible to focus light on the specimen to be observed, and, thus, sufficient amount of light may not be projected thereon.
In other words, the thickness of the movable microscope stage becomes large, the objective lens as well as the condenser is not approachable sufficiently to the specimen can, so that the objective lens as well as the condenser can not be bring closer to the specimen sufficiently to focus thereon.
It is an object of the present invention is to provide a microscope stage capable of always heating entire culture vessels such as well plates of various shapes or sizes, and capable of bringing the objective lens as well as the condenser closer to the specimen to be observed sufficiently to focus thereon even when the microscope is a high powered one. Further, it is another object of the present invention is to provide a microscope observing unit forming an enclosed space in combination with the drive base of the microscope stage, and capable of controlling atmosphere in temperature and/or humidity within the enclosed space.